ELECTROCHEMISTRYELECTROCHEMISTRY

CHEMICAL CHEMICAL SUBSTANCESSUBSTANCES

ELECTROLYTES NON-ELECTROLYTES

Substances that can conduct electricity when they are in molten state or aqueous and undergo chemical changes

Substances that cannot conduct electricity either in molten state or aqueous

Example:

Ionic substances

(i) Dilute acid solution

(ii) Dilute alkaline solution

(iii) Molten salts

(iv) Aqueous salt solution

Example:

Covalent substances

(i) Naphthalene

(ii) Sugar solution

(iii) Latex

(iv) Hydrogen chloride in organic solvents

Heat

Molten lead (II) iodide

BulbCarbon electrodes

Heat

Solid lead (II) iodide

Carbon electrodes

Bulb

………….

…. ..… ………..…. ….

… ……….…. …. …. ….…. …. ….….….….….

switchswitch

•Do not conduct electricity

•This is because the ions are held in a fixed crystal lattice.

•They are held with the strong electrostatic forces of attraction

•Do not freely move

I - Pb 2+

Pb 2+ Pb 2+ I -I -

I -

I -I - Pb 2+

Pb 2+

Pb 2+

Pb 2+

Solid lead (II) iodide

IN A SOLID STATEIN A SOLID STATE

Molten lead (II) iodide

I -

Pb 2+

Pb 2+ Pb 2+

I -I -

•Can conduct electricity

•This is because the presence of moving ions. The ions are free to move in the molten or aqueous solution

IN A MOLTEN STATEIN A MOLTEN STATE

ELECTROLYTES AND NON ELECTROLYTES AND NON ELECTROLYTESELECTROLYTES

Classify the following chemicals into electrolytes or non-Classify the following chemicals into electrolytes or non-electrolyteselectrolytes

Potassium chloride, KCl solutionPotassium chloride, KCl solution Molten lead (II) bromide, PbBrMolten lead (II) bromide, PbBr22

Glucose solutionGlucose solution TrichloromethaneTrichloromethane Molten zinc oxide, ZnOMolten zinc oxide, ZnO Sodium chloride, NaCl solutionSodium chloride, NaCl solution Ammonia in tetrachloromethaneAmmonia in tetrachloromethane

A process of A process of breaking downbreaking down the chemical the chemical compounds into their constituent elements using compounds into their constituent elements using electric currentelectric current

Example:Example:Molten aluminium oxide (I) aluminium (s) + oxygen (g)

Copper (II) chloride (aq) copper (s) + chlorine (g)Electric current

Electric current

ELECTROLYSISELECTROLYSIS

ELECTROLYTIC CELLELECTROLYTIC CELL

Electrolyte

e-

e- e-

e-

Electrode Electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

- +

Anion Cation

The set of apparatus needed to conduct The set of apparatus needed to conduct electrolysiselectrolysis

It consists of a It consists of a batterybattery, an , an electrolyteelectrolyte, and , and two two electrodeselectrodes (anode and cathode) (anode and cathode)

AnodeAnode - the electrode which is connected to the - the electrode which is connected to the positive terminal of an electric source in the positive terminal of an electric source in the electrolytic cellelectrolytic cell

CathodeCathode - the electrode which is connected to - the electrode which is connected to the negative terminal of an electric source in the the negative terminal of an electric source in the electrolytic cellelectrolytic cell

ELECTROLYTIC CELLELECTROLYTIC CELL

ANODEANODE

(POSITIVE ELECTRODE)(POSITIVE ELECTRODE)

CATHODE

(NEGATIVE ELECTRODE)(NEGATIVE ELECTRODE)

Anions (negative ions)Anions (negative ions) will be pulled towards will be pulled towards the anode (positive the anode (positive electrode)electrode)

Cations (positive ions)Cations (positive ions) will will be pulled towards the be pulled towards the cathode (negative cathode (negative electrode)electrode)

At the anode, anions At the anode, anions will be discharged by will be discharged by releasingreleasing the electrons the electrons to the anodeto the anode

At the cathode, cations will At the cathode, cations will be discharged by be discharged by receivingreceiving the electrons the electrons from the from the cathodecathode

During electrolysisDuring electrolysis::

ELECTROLYSIS OF MOLTEN ELECTROLYSIS OF MOLTEN COMPOUNDSCOMPOUNDS

QUESTIONSQUESTIONS

(a) Molten zinc chloride (I)

(b) Molten aluminium (III) bromide

(c) Molten zinc (II) iodide

(d) Molten lead (II) oxide Electric current

Electric current

Electric current

Electric current

Example 1Example 1

Molten Potassium Iodide, KI

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

The ions that presents in electrolyte are:

(i) Anion:

(ii) Cation:

Example 2Example 2

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

The ions that presents in electrolyte are:

(i) Anion:

(ii) Cation:

Molten zinc oxide, ZnO

Example 3Example 3

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

The ions that presents in electrolyte are:

(i) Anion:

(ii) Cation:

Molten lead (II) bromide, PbBr2

Example 4Example 4

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

The ions that presents in electrolyte are:

(i) Anion:

(ii) Cation:

Molten lead (II) oxide, PbO

Example 5Example 5

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

The ions that presents in electrolyte are:

(i) Anion:

(ii) Cation:

Molten zinc (II) chloride, ZnCl2

ELECTROLYSIS OF MOLTEN ELECTROLYSIS OF MOLTEN COMPOUNDCOMPOUND

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

The ions that presents in electrolyte are:

(i) Anion:

(ii) Cation:

Molten lead (II) bromide, PbBr2

Molten lead (II) bromide

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

…… ……………… …..

…. ….. …… … ….

.. . …….. …… … …

……………………………………...

Pb2+

Pb2+

Pb2+

Pb2+

Br-

Br-

Br-

Br-

ELECTROLYSIS OF MOLTEN ELECTROLYSIS OF MOLTEN COMPOUNDCOMPOUND

PbPb2+2+ are attracted to the cathode are attracted to the cathode BrBr-- are attracted to anode are attracted to anode

BrBr-- discharge by releasing electrons to the discharge by releasing electrons to the anodeanode

CATHODECATHODE

(NEGATIVE ELECTRODE)(NEGATIVE ELECTRODE)

ANODEANODE

(POSITIVE ELECTRODE)(POSITIVE ELECTRODE)

Br- Br + e-

Neutral atoms form and combine to form neutral bromine molecules

Br + Br Br2 (g)

The half reaction at anode can be represented by the half equation

2Br- (l) Br2 (g) + 2e-

Pb2+ discharge by receiving electrons (provided by the battery) at the cathode to form neutral lead atoms

Pb2+(l) + 2e- Pb (s)

The half reaction at cathode can be represented by the half equation

The Half Equation:

Cathode:

Anode:

Overall Equation:

2Br- (l) Br2 (g) + 2e-

Pb2+(l) + 2e- Pb (s)

Pb2+(l) + 2Br- (l) Pb(s) + Br2 (g)

Write the half equation and the overall Write the half equation and the overall equation for the electrolysis of these equation for the electrolysis of these molten compounds :molten compounds :

(A) Molten potassium iodide, KI(A) Molten potassium iodide, KI

(B) Molten zinc (II) chloride, ZnCl(B) Molten zinc (II) chloride, ZnCl22

(C) Molten lead (II) oxide, PbO(C) Molten lead (II) oxide, PbO

ELECTROLYSIS OF AQUEOUS ELECTROLYSIS OF AQUEOUS SOLUTIONSOLUTION

Water molecules in an aqueous solution can slightly dissociate to produce H+ and OH-

H2O H+ (aq) + OH-(aq)

So, aqueous solution contains H+ and OH- and electrolyte ions

Examples:

Aqueous SolutionAqueous Solution

Ions presentIons present

AnionAnion CationCation

NaCl solutionNaCl solution ClCl-- , OH , OH-- NaNa++ , H , H++

CuSOCuSO44 solution solution

HNOHNO33 solution solution

If they are more than one cations or anions If they are more than one cations or anions attracted, the choice of ion to be discharged attracted, the choice of ion to be discharged

depends on :depends on :

Positions of the ions Positions of the ions in the in the electrochemical serieselectrochemical series

Types of Types of electrodeselectrodes

Concentration of ionsConcentration of ions in the electrolytein the electrolyte

Electrochemical Series (pg.101)Electrochemical Series (pg.101)

CATIONSCATIONS

KK + + NaNa++

CaCa2+2+

MgMg2+2+

Al Al 3+3+

ZnZn2+2+

FeFe2+2+

SnSn2+2+

PbPb2+2+

HH++

CuCu2+2+

AgAg++

Tendency to discharge increases

ANIONSANIONS

FF--

SOSO4422--

NONO33--

ClCl--

BrBr--

II--

OHOH--

Positions of the ions Positions of the ions in the electrochemical seriesin the electrochemical series

Copper (II) chloride solution, CuCl2

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

H+

Cu2+

Cu2+

H+

Cl-

Cl-OH-

OH-

Positions of the ions Positions of the ions in the electrochemical seriesin the electrochemical series

Observation Observation andand

ProductProduct

HH++ , Cu , Cu2+2+

CuCu2+2+are preferred to be dischargedare preferred to be discharged

(Cu(Cu2+ 2+ is below His below H++ in the ES) in the ES)

OHOH-- , Cl , Cl- -

OHOH-- are preferred to be discharged are preferred to be discharged

(OH(OH-- is below Cl is below Cl- - in the ES)in the ES)

Ions that are Ions that are attractedattracted

CathodeCathodeAnodeAnode

Bubbles of gas, OBubbles of gas, O22

is releasedis releasedBrown solid, Cu is formedBrown solid, Cu is formed

Half Half equationequation

4OH4OH- - (aq) 2H(aq) 2H22O (l) + OO (l) + O22 (g) (g)

+ 4 e+ 4 e--

CuCu2+ 2+ (aq) + 2e(aq) + 2e-- Cu (s) Cu (s)

Concentration of ions in Concentration of ions in electrolyte solutionselectrolyte solutions

Concentration of ions in electrolyte solution also Concentration of ions in electrolyte solution also can affects the choice of ions to be dischargedcan affects the choice of ions to be discharged

An ion that is An ion that is more concentratedmore concentrated is preferably is preferably dischargeddischarged

AnodeAnode – the ions to be discharged is – the ions to be discharged is determined by determined by the concentration of ionsthe concentration of ions

CathodeCathode – the ions to be discharged is – the ions to be discharged is determined by determined by the position of the ion in the the position of the ion in the E.SE.S

Concentration of ions in Concentration of ions in electrolyte solutionselectrolyte solutions

Concentrated copper (II) chloride solution, CuCl2

e-

e- e-

e-

Carbon electrode

Carbon electrode

- (cathode)+ (anode)

Cu2+

H+Cl-

OH-

Concentration of ions in Concentration of ions in electrolyte solutionselectrolyte solutions

Observation Observation and and

ProductProduct

HH++ , Cu , Cu2+2+

CuCu2+2+are preferred to be dischargedare preferred to be discharged

(Cu(Cu2+ 2+ is below His below H++ in the ES) in the ES)

OHOH-- , Cl , Cl--

ClCl-- are preferred to be discharged are preferred to be discharged

(Cl(Cl- - is more concentrated) is more concentrated)

Ions that are Ions that are attractedattracted

CathodeCathodeAnodeAnode

Yellow bubbles gas, ClYellow bubbles gas, Cl22

is releasedis released

Brown solid, Cu is formedBrown solid, Cu is formed

Half Half equationequation

2Cl2Cl- - (aq) Cl(aq) Cl22 (g) + 2 e (g) + 2 e--CuCu2+ 2+ (aq) + 2e(aq) + 2e-- Cu (s) Cu (s)

Types of ElectrodesTypes of Electrodes

Silver nitrate, AgNO3 solution

e-

e- e-

e-

Silver plate Carbon electrode

- (cathode)+ (anode)

Ag+

AgAg+

Types of ElectrodesTypes of Electrodes

AgAg+ + (aq) + e(aq) + e-- Ag (s) Ag (s)

Observation Observation and and

ProductProduct

AgAg++ receives one electron to receives one electron to form metal atomsform metal atoms

Ag atom releases one electron to form Ag atom releases one electron to form AgAg++

IonsIons

CathodeCathodeAnodeAnode

The silver plate corrodesThe silver plate corrodes Grey silver solid, Ag is Grey silver solid, Ag is formedformed

Half Half equationequation

Ag (s) AgAg (s) Ag+ + (aq) + e(aq) + e--

Exercises Exercises

Electrolysis of copper (II) sulphate, CuSOElectrolysis of copper (II) sulphate, CuSO44, solution , solution

using carbon electrodesusing carbon electrodes

AnodeAnode CathodeCathode

Ions that are Ions that are attractedattracted

Ion that are Ion that are prefer to be prefer to be dischargeddischarged

ObservationObservation

ProductProduct

Half equationHalf equation

ExercisesExercises

Electrolysis of concentrated potassium chloride, KCl, Electrolysis of concentrated potassium chloride, KCl, solution using carbon electrodessolution using carbon electrodes

AnodeAnode CathodeCathode

Ions that areIons that are

attractedattracted

Ion that are Ion that are prefer to be prefer to be dischargeddischarged

ObservationObservation

ProductProduct

Half equationHalf equation

ExercisesExercises

Electrolysis of nickel (II) sulphate, NiSOElectrolysis of nickel (II) sulphate, NiSO44, solution , solution

using nickel plate as anode and cathodeusing nickel plate as anode and cathode

AnodeAnode CathodeCathode

Half equationHalf equation

ObservationObservation

ProductProduct

Factors that influence electrolysis Factors that influence electrolysis of aqueous solutions of aqueous solutions

TYPES OF ELECTRODESTYPES OF ELECTRODES

POSITION OF IONS POSITION OF IONS

IN THE ELECTROCHEMICAL IN THE ELECTROCHEMICAL SERIESSERIES

CONCENTRATION OF IONS CONCENTRATION OF IONS

IN THE ELECTROLYTE IN THE ELECTROLYTE SOLUTIONSOLUTION

USES OF ELECTROLYSISUSES OF ELECTROLYSIS

IN INDUSTRIESIN INDUSTRIES

Reacts with a Reacts with a carbonate metal metal to form carbon to form carbon dioxide gas (COdioxide gas (CO22),water ),water

(H(H22O) and saltO) and salt

ELECTROPLATING ELECTROPLATING OF METALSOF METALS

EXTRACTIONEXTRACTION OF METALS OF METALS

PURIFICATIONPURIFICATION OF OF METALSMETALS

Extraction of MetalsExtraction of Metals Electrolysis can be used to extract metals from Electrolysis can be used to extract metals from

their orestheir ores Reactive metals that are Reactive metals that are more reactivemore reactive than C than C

such as (K, Na, Ca, Mg, Al) cannot be such as (K, Na, Ca, Mg, Al) cannot be extracted through extracted through heatingheating of their metal of their metal oxides with Coxides with C

They need to be extracted from their molten They need to be extracted from their molten ores using the ores using the electrolysis processelectrolysis process

In this process:In this process:

ElectrolyteElectrolyte The molten oreThe molten ore

AnodeAnode Carbon electrodeCarbon electrode

CathodeCathode Carbon electrodeCarbon electrode

Example:Example:

Extraction of aluminium from electrolysis Extraction of aluminium from electrolysis of molten aluminium oxide, Alof molten aluminium oxide, Al22OO33

Purification of MetalsPurification of Metals Metals that have been extracted from their Metals that have been extracted from their

ores are normally not pure. They contains ores are normally not pure. They contains impurities which need to be removedimpurities which need to be removed

These metals can be purified by electrolysis These metals can be purified by electrolysis processprocess

In the purification processIn the purification process

ElectrolyteElectrolyte The solution that contains The solution that contains

the metal ionsthe metal ions

AnodeAnode The impure metal plateThe impure metal plate

CathodeCathode The pure metal plateThe pure metal plate

Example:Example:

Purification of copperPurification of copper

Electroplating of MetalsElectroplating of Metals Many types of metals can be plated with other Many types of metals can be plated with other

metals through electrolysis.metals through electrolysis. The aim of metal plating through electrolysis The aim of metal plating through electrolysis

includes:includes:

(i) making the metal more (i) making the metal more resistantresistant to to corrosioncorrosion

(ii) making the metal appear more (ii) making the metal appear more attractiveattractive In the electroplating processIn the electroplating process

ElectrolyteElectrolyte The solution which contains The solution which contains ions of plating metalions of plating metal

AnodeAnode Plating metalPlating metal

CathodeCathode Metal to be platedMetal to be plated

Example:Example:

Electroplating of a iron spoon with copper Electroplating of a iron spoon with copper metalmetal

Copper (II) Copper (II) sulphate sulphate solution solution

ELECTROLYTIC CELLELECTROLYTIC CELL

e-

e- e-

e-

CarbonCarbon

electrodeelectrodeCarbonCarbon

electrode electrode

- (cathode) + (anode)

VOLTAIC CELLVOLTAIC CELL

CuCu

Copper (II) Copper (II) sulphatesulphate

V

e-

e- e-

e-

- (anode)- (anode) + (cathode)+ (cathode)

ZnZn

Zn (s) ZnZn (s) Zn2+ 2+ (aq) + 2e(aq) + 2e-- CuCu2+ 2+ (aq) + 2e(aq) + 2e- - Cu Cu (s)(s)

VOLTAIC CELLVOLTAIC CELL

Also known as Also known as galvanic cellgalvanic cell Has Has two different metalstwo different metals which are immersed which are immersed

into an electrolyte and connected by wireinto an electrolyte and connected by wire Produces electrical energy from the chemical Produces electrical energy from the chemical

reactions occurring inside the cellreactions occurring inside the cell

Example : Daniell cellExample : Daniell cell

Chemical energy electrical energyChemical energy electrical energy

DANIELL CELLDANIELL CELL

V

Dilute HDilute H22SOSO44

(Salt bridge)(Salt bridge)

Zn (-)Zn (-) Cu (+)Cu (+)

CuSOCuSO44

solutionsolution

ZnSOZnSO44 solution solution

(Anode)(Anode) (Cathode)(Cathode)

e- e-

e- e-

Zn (s) ZnZn (s) Zn2+ 2+ (aq) + 2e(aq) + 2e-- CuCu2+ 2+ (aq) + 2e(aq) + 2e- - Cu Cu (s)(s)

SALT BRIDGESALT BRIDGE Can be made from any electrolyte that does not Can be made from any electrolyte that does not

react with the electrodes in Daniell Cellreact with the electrodes in Daniell Cell Function :Function :

(i) to allow the flow of the ions so the electric (i) to allow the flow of the ions so the electric current is completedcurrent is completed

ExampleExample::

(i) diluted H(i) diluted H22SOSO44

(ii) sodium nitrate, NaNO(ii) sodium nitrate, NaNO3 3 solutionsolution

(iii) Potassium chloride solution, KCl(iii) Potassium chloride solution, KCl

DANIELL CELLDANIELL CELL

V

Porous Porous pot pot contains contains ZnSOZnSO44

Zn (-)Zn (-) Cu (+)Cu (+)

CuSOCuSO4 4

solutionsolution

(Anode)(Anode)(Cathode)(Cathode)

e- e-

e- e-

Reactivity SeriesReactivity Series

KK NaNaCaCaMgMgAl Al ZnZnFeFeSnSnPbPbHH

CuCuAgAg

METALSMORE

ELECTROPOSITIVE

(negative terminal)

MORE ELECTRONEGATIVE

(positive terminal)

Anode and CathodeAnode and Cathode

AnodeAnode – the electrode where the process of – the electrode where the process of donation of electronsdonation of electrons takes place takes place

CathodeCathode – the electrode where the process of – the electrode where the process of receiving of electronsreceiving of electrons takes place takes place

Negative terminal – Cathode

Positive terminal - Anode

Negative terminal – Anode

Positive terminal - Cathode

ELECTROLYTIC CELLELECTROLYTIC CELL VOLTAIC CELLVOLTAIC CELL

ELECTROCHEMICAL SERIESELECTROCHEMICAL SERIES

Electrochemical Series (pg.101)Electrochemical Series (pg.101)

CATIONSCATIONS

KK + + NaNa++

CaCa2+2+

MgMg2+2+

Al Al 3+3+

ZnZn2+2+

FeFe2+2+

SnSn2+2+

PbPb2+2+

HH++

CuCu2+2+

AgAg++

Tendency to discharge increases

ANIONSANIONS

FF--

SOSO4422--

NONO33--

ClCl--

BrBr--

II--

OHOH--

ELECTROCHEMICAL ELECTROCHEMICAL SERIESSERIES

An arrangement of metals, based on the tendency of each metal atom to donate electrons

The higher the position of a metal in the electrochemical series:

ELECTROCHEMICAL SERIESELECTROCHEMICAL SERIES

More electropositiveMore electropositive The The greatergreater the tendency the tendency of the metal atoms of the metal atoms to to donate electronsdonate electrons

PRINCIPLES DURING CONSTRUCTING PRINCIPLES DURING CONSTRUCTING THE ELECTROCHEMICAL SERIESTHE ELECTROCHEMICAL SERIES

Potential differences Potential differences between two metals in the between two metals in the voltaic cellvoltaic cell

Ability of a metal to Ability of a metal to displace another metal displace another metal from its salt solutionfrom its salt solution

The value of the potential difference of a simple voltaic The value of the potential difference of a simple voltaic cell is affected by the cell is affected by the position of the metalsposition of the metals in the in the electrochemical serieselectrochemical series

When two When two different metalsdifferent metals are immersed in an electrolyte are immersed in an electrolyte solution, a solution, a potential differencepotential difference is generated is generated

The The largerlarger the value of the cell voltage is produced the value of the cell voltage is produced

The The furtherfurther the two metals in the electrochemical series the two metals in the electrochemical series

Potential differences between two Potential differences between two metals in the voltaic cellmetals in the voltaic cell

Potential differences between two Potential differences between two metals in the voltaic cellmetals in the voltaic cell

The metal that is The metal that is more more electropositiveelectropositive

Located Located higherhigher in the in the electrochemical serieselectrochemical series

Act as the Act as the negative terminalnegative terminal

The metal that is The metal that is less less electropositiveelectropositive

Located Located lowerlower in the in the electrochemical serieselectrochemical series

Act as the Act as the positivepositive terminal terminal

Potential differences between two Potential differences between two metals in the voltaic cellmetals in the voltaic cell

Mg

Zn

Pb

Cu

Ag

3.0 V1.1 V

0.4 V

0.5 V

Predict the negative terminal, positive terminal and cell voltage of the following voltaic cell

(a) Magnesium and silver (c) zinc and lead

(b) Magnesium and zinc (d) zinc and silver

Metal DisplacementMetal Displacement

A metal that is more electropositive can displace another metal which is less electropositive from its salt solution

This reaction – displacement reaction

A metal that is located higher in the electrochemical series can displace another metal which is located lower in the electrochemical series from its salt solution

Metal DisplacementMetal Displacement

Example:

Zinc, Zn can displace copper, Cu, from copper (II) nitrate, Cu(NO3)2

solution

Zn (s) + Cu(NO3)2 (aq) Zn(NO3)2 (aq) + Cu (s)

• Zn is more electropositive than copper

• Zn can displace Cu from copper (II) nitrate, Cu(NO3)2 solution

• The zinc, Zn, will dissolve and brown copper solid, Cu, will form

Metal displaced

IMPORTANCE OF THE IMPORTANCE OF THE ELECTROCHEMICAL ELECTROCHEMICAL

SERIESSERIES

Reacts with a Reacts with a carbonate metal metal to form carbon to form carbon dioxide gas (COdioxide gas (CO22),water ),water

(H(H22O) and saltO) and salt

It can determined the terminals of voltaic cells

It can determined the cell voltage for a pair of

metals

It can predicted the potential of a metal to displace another metal

from its solution